EFFECT OF ORGANIC CHROMIUM ON GROWTH AND CARBOHYRATE UTILIZATION IN HYBRID TILAPIA OREOCHROMIS NILOTICUS@ O.AUREUS

An 82 week growth trial was conducted to investigate the effect of different forms of organic chromium on glucose and starch utilization in hybrid tilapia Oreochromis niloticus@ O. aureus. The forms of Cr were chromium nicotinate acid(Cr-Nic), chromium picolinate acid(Cr-Pic), chromium methionine(Cr-Met)and chromium acetic acid(Cr-Ac). The inclusion level of Cr was 2mg/kg diet. Fishes of 1.4g were reared in a still water system and fed at 6%-8% of body weight 4 meals/day. Significantly(P0.05)higher specific growth rate were observed in fish fed the glucose diet with Cr-Nic and Cr-Pic, while no significant difference was observed in those fed the starch diet(P0.05). Feed efficiencies in fish fed diets with Cr-Nic and Cr-Pic were significantly higher than those fed diets without Cr. The contents of body moisture in fish fed the glucose diet were significantly lower than those fed the starch diet, while the contents of body lipid were significantly higher. Dorsal muscle phosphfructokinase activity in fish fed the glucose diet with Cr-Pic was significantly higher than that fed the starch diet with Cr-Pic, whereas hepatic fructose-1,6-phophatase activity was significantly lower. The results suggested that organic Cr could improve glucose utilization significantly in hybrid tilapia under the present experimental condition. There was no significant difference between glucose and starch utilization in hybrid tilap, while dietary carbohydrate sources could affect the whole body composition.